Because of their structure, conventional fountain pens often leak ink when subjected to changes in temperature and/or pressure.
A change in temperature occurs when a user is writing, as the user's hand warms the body of the fountain pen.
A change in pressure occurs when traveling by plane, as a result of the constant changes in altitude of the aircraft.
To solve this problem, a fountain pen of the aforementioned type has been developed in which a cap is provided to protect the nib when the fountain pen is not in use, the cap cooperating with the valve by means of lugs that close the ink flow passage when the cap is in place on the pen.
However, it has been observed that when the cap is opened there is always some ink leakage, even if minimal.
It has also been found that in such a fountain pen, the flow of ink through the various elements is not optimal, which can interfere with writing smoothly.